The present invention relates to a yarn winding apparatus of the type having a rotatable revolver which mounts a pair of winding spindles, and wherein the spindles are serially delivered to a winding position and a doffing position as the revolver is sequentially rotated.
In the known winding machines of the described type, the growth or build in the diameter of the package is in the course of winding a package accommodated by means of an evasive movement of the package or of the pressure roll. In this connection, the abutment force between the package and the pressure roll is predetermined by hydraulic or pneumatic force-transmitters and is held substantially at a constant value during winding.
In the case of the winding device known from U.S. Pat. No. 4,298,171, the winding spindle is moved away from the fixed pressure roll by means of the rotary motion of a revolver during winding. In this connection, the winding spindle is supported on a rocker which is capable of being pivoted relative to the revolver by means of a force-transmitter. In the winding region, the winding spindle is pressed with the package to be formed against the fixed pressure roll. In this connection, the rotary motion of the revolver for the purpose of forming the package is controlled in such a way that the relative location of the rocker on the revolver remains unchanged. The abutment force between the pressure roll and the package is predetermined by the force-transmitter. In this connection, the winding region is dependent on the magnitude of the diameter of the revolver.
In the case of the winding machine known from DE 25 23 771 and corresponding U.S. Pat. No. 4,114,820, a winding spindle that receives the package is moved away in a straight line from a pressure roll by means of a linear guide mechanism during winding. In this connection, the effective direction of the abutment force of the pressure roll relative to the surface of the package remains constant. The pressure force is determined by means of a pneumatic cylinder.
In the case of the known winding machines, the abutment force between the package and the pressure roll is applied by the same control device that also controls the evasive movement between the pressure roll and the winding spindle. In this connection undesirable changes in the abutment force arise by reason of stick-slip effects.
In the course of winding a package, it is in fact desirable that the pressure force does not remain constant during the build of the package. For instance, a low pressure force is often required at the beginning of winding in order not to press the initial layers into one another. In the further course of winding a higher pressure force is required, in order, for example, to increase the packing density. However, with a view to avoiding bulging of the package it is also necessary to maintain regions having low pressure forces during winding.
It is therefore an object of the invention to develop an improved winding machine of the described type, wherein the yarn is wound in stages with, in each instance, different but constant abutment forces between the package and the pressure roll.
It is also an objective of the invention to provide a winding apparatus of the described type which has a compact style of construction and which is able to wind large packages.